You might take a look on the Nite-Ize website under "Mobile Accessories," and the ebags.com website.

And with the zillions of MP3 and digital camera pouches available in every conceivable shape, size and color, might find something there. Even though many come with a shoulder strap, most are also designed for belt-carry. The secondary advantage to such cases is that they look less "tactical" and might fit in more with your day-to-day environment.